Em Sun, 3 Mar 2013 20:40:57 +0100
Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu:
> The webcam "SpeedLink VAD Laplace" (em2765 + ov2640) uses a special algorithm
> for i2c communication with the sensor, which is connected to a second i2c bus.
>
> We don't know yet how to find out which devices support/use it.
> It's very likely used by all em25xx and em276x+ bridges.
> Tests with other em28xx chips (em2820, em2882/em2883) show, that this
> algorithm always succeeds there although no slave device is connected.
>
> The algorithm likely also works for real I2C client devices (OV2640 uses SCCB),
> because the Windows driver seems to use it for probing Samsung and Kodak
> sensors.
>
> Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
> ---
> drivers/media/usb/em28xx/em28xx-cards.c | 6 +-
> drivers/media/usb/em28xx/em28xx-i2c.c | 164 +++++++++++++++++++++++++++----
> drivers/media/usb/em28xx/em28xx.h | 7 ++
> 3 Dateien geändert, 159 Zeilen hinzugefügt(+), 18 Zeilen entfernt(-)
>
> diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
> index 5a5b637..75d4aef 100644
> --- a/drivers/media/usb/em28xx/em28xx-cards.c
> +++ b/drivers/media/usb/em28xx/em28xx-cards.c
> @@ -3103,7 +3103,11 @@ static int em28xx_init_dev(struct em28xx *dev, struct usb_device *udev,
> return retval;
> }
> /* Configure i2c bus */
> - if (!dev->board.is_em2800) {
> + if (dev->board.is_em2800) {
> + dev->i2c_algo_type = EM28XX_I2C_ALGO_EM2800;
> + } else {
> + dev->i2c_algo_type = EM28XX_I2C_ALGO_EM28XX;
> +
> retval = em28xx_write_reg(dev, EM28XX_R06_I2C_CLK, dev->board.i2c_speed);
> if (retval < 0) {
> em28xx_errdev("%s: em28xx_write_reg failed!"
> diff --git a/drivers/media/usb/em28xx/em28xx-i2c.c b/drivers/media/usb/em28xx/em28xx-i2c.c
> index 44bef43..6e86ffc 100644
> --- a/drivers/media/usb/em28xx/em28xx-i2c.c
> +++ b/drivers/media/usb/em28xx/em28xx-i2c.c
> @@ -5,6 +5,7 @@
> Markus Rechberger <mrechberger@xxxxxxxxx>
> Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>
> Sascha Sommer <saschasommer@xxxxxxxxxx>
> + Copyright (C) 2013 Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
>
> This program is free software; you can redistribute it and/or modify
> it under the terms of the GNU General Public License as published by
> @@ -270,6 +271,114 @@ static int em28xx_i2c_check_for_device(struct em28xx *dev, u16 addr)
> }
>
> /*
> + * em25xx_bus_B_send_bytes
> + * write bytes to the i2c device
> + */
> +static int em25xx_bus_B_send_bytes(struct em28xx *dev, u16 addr, u8 *buf,
> + u16 len)
> +{
> + int ret;
> +
> + if (len < 1 || len > 64)
> + return -EOPNOTSUPP;
> + /* NOTE: limited by the USB ctrl message constraints
> + * Zero length reads always succeed, even if no device is connected */
> +
> + /* Set register and write value */
> + ret = dev->em28xx_write_regs_req(dev, 0x06, addr, buf, len);
> + /* NOTE:
> + * 0 byte writes always succeed, even if no device is connected. */
> + if (ret != len) {
> + if (ret < 0) {
> + em28xx_warn("writing to i2c device at 0x%x failed "
> + "(error=%i)\n", addr, ret);
> + return ret;
> + } else {
> + em28xx_warn("%i bytes write to i2c device at 0x%x "
> + "requested, but %i bytes written\n",
> + len, addr, ret);
> + return -EIO;
> + }
> + }
> + /* Check success */
> + ret = dev->em28xx_read_reg_req(dev, 0x08, 0x0000);
> + /* NOTE: the only error we've seen so far is
> + * 0x01 when the slave device is not present */
> + if (ret == 0x00) {
> + return len;
> + } else if (ret > 0) {
> + return -ENODEV;
> + }
> +
> + return ret;
> + /* NOTE: With chips which do not support this operation,
> + * it seems to succeed ALWAYS ! (even if no device connected) */
> +}
> +
> +/*
> + * em25xx_bus_B_recv_bytes
> + * read bytes from the i2c device
> + */
> +static int em25xx_bus_B_recv_bytes(struct em28xx *dev, u16 addr, u8 *buf,
> + u16 len)
> +{
> + int ret;
> +
> + if (len < 1 || len > 64)
> + return -EOPNOTSUPP;
> + /* NOTE: limited by the USB ctrl message constraints
> + * Zero length reads always succeed, even if no device is connected */
> +
> + /* Read value */
> + ret = dev->em28xx_read_reg_req_len(dev, 0x06, addr, buf, len);
> + /* NOTE:
> + * 0 byte reads always succeed, even if no device is connected. */
> + if (ret != len) {
> + if (ret < 0) {
> + em28xx_warn("reading from i2c device at 0x%x failed "
> + "(error=%i)\n", addr, ret);
> + return ret;
> + } else {
> + em28xx_warn("%i bytes requested from i2c device at "
> + "0x%x, but %i bytes received\n",
> + len, addr, ret);
> + return -EIO;
> + }
> + }
> + /* Check success */
> + ret = dev->em28xx_read_reg_req(dev, 0x08, 0x0000);
> + /* NOTE: the only error we've seen so far is
> + * 0x01 when the slave device is not present */
> + if (ret == 0x00) {
> + return len;
> + } else if (ret > 0) {
> + return -ENODEV;
> + }
> +
> + return ret;
> + /* NOTE: With chips which do not support this operation,
> + * it seems to succeed ALWAYS ! (even if no device connected) */
> +}
> +
> +/*
> + * em25xx_bus_B_check_for_device()
> + * check if there is a i2c device at the supplied address
> + */
> +static int em25xx_bus_B_check_for_device(struct em28xx *dev, u16 addr)
> +{
> + u8 buf;
> + int ret;
> +
> + ret = em25xx_bus_B_recv_bytes(dev, addr, &buf, 1);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> + /* NOTE: With chips which do not support this operation,
> + * it seems to succeed ALWAYS ! (even if no device connected) */
> +}
> +
> +/*
> * em28xx_i2c_xfer()
> * the main i2c transfer function
> */
> @@ -277,7 +386,9 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> struct i2c_msg msgs[], int num)
> {
> struct em28xx *dev = i2c_adap->algo_data;
> - int addr, rc, i, byte;
> + int addr, i, byte;
> + int rc = -EOPNOTSUPP;
> + enum em28xx_i2c_algo_type algo_type = dev->i2c_algo_type;
>
> if (num <= 0)
> return 0;
> @@ -290,10 +401,13 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> i == num - 1 ? "stop" : "nonstop",
> addr, msgs[i].len );
> if (!msgs[i].len) { /* no len: check only for device presence */
> - if (dev->board.is_em2800)
> - rc = em2800_i2c_check_for_device(dev, addr);
> - else
> + if (algo_type == EM28XX_I2C_ALGO_EM28XX) {
> rc = em28xx_i2c_check_for_device(dev, addr);
> + } else if (algo_type == EM28XX_I2C_ALGO_EM2800) {
> + rc = em2800_i2c_check_for_device(dev, addr);
> + } else if (algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B) {
> + rc = em25xx_bus_B_check_for_device(dev, addr);
> + }
That seems too messy.
IMO, the best is to create 3 different em28xx_i2c_xfer() routines:
one for em2800, one for "standard" I2c protocol, and another one for
this em25xx one. Then, all you need to do is to embed
static struct i2c_algorithm into struct em28xx and fill
em28xx_algo.master_transfer to point to the correct xfer.
That makes the code more readable and remove a little faster by removing
the unneeded ifs from the code.
> if (rc == -ENODEV) {
> if (i2c_debug)
> printk(" no device\n");
> @@ -301,14 +415,19 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> }
> } else if (msgs[i].flags & I2C_M_RD) {
> /* read bytes */
> - if (dev->board.is_em2800)
> - rc = em2800_i2c_recv_bytes(dev, addr,
> + if (algo_type == EM28XX_I2C_ALGO_EM28XX) {
> + rc = em28xx_i2c_recv_bytes(dev, addr,
> msgs[i].buf,
> msgs[i].len);
> - else
> - rc = em28xx_i2c_recv_bytes(dev, addr,
> + } else if (algo_type == EM28XX_I2C_ALGO_EM2800) {
> + rc = em2800_i2c_recv_bytes(dev, addr,
> msgs[i].buf,
> msgs[i].len);
> + } else if (algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B) {
> + rc = em25xx_bus_B_recv_bytes(dev, addr,
> + msgs[i].buf,
> + msgs[i].len);
> + }
> if (i2c_debug) {
> for (byte = 0; byte < msgs[i].len; byte++)
> printk(" %02x", msgs[i].buf[byte]);
> @@ -319,15 +438,20 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
> for (byte = 0; byte < msgs[i].len; byte++)
> printk(" %02x", msgs[i].buf[byte]);
> }
> - if (dev->board.is_em2800)
> - rc = em2800_i2c_send_bytes(dev, addr,
> - msgs[i].buf,
> - msgs[i].len);
> - else
> + if (algo_type == EM28XX_I2C_ALGO_EM28XX) {
> rc = em28xx_i2c_send_bytes(dev, addr,
> msgs[i].buf,
> msgs[i].len,
> i == num - 1);
> + } else if (algo_type == EM28XX_I2C_ALGO_EM2800) {
> + rc = em2800_i2c_send_bytes(dev, addr,
> + msgs[i].buf,
> + msgs[i].len);
> + } else if (algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B) {
> + rc = em25xx_bus_B_send_bytes(dev, addr,
> + msgs[i].buf,
> + msgs[i].len);
> + }
> }
> if (rc < 0) {
> if (i2c_debug)
> @@ -589,10 +713,16 @@ error:
> static u32 functionality(struct i2c_adapter *adap)
> {
> struct em28xx *dev = adap->algo_data;
> - u32 func_flags = I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> - if (dev->board.is_em2800)
> - func_flags &= ~I2C_FUNC_SMBUS_WRITE_BLOCK_DATA;
> - return func_flags;
> +
> + if ((dev->i2c_algo_type == EM28XX_I2C_ALGO_EM28XX) ||
> + (dev->i2c_algo_type == EM28XX_I2C_ALGO_EM25XX_BUS_B)) {
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> + } else if (dev->i2c_algo_type == EM28XX_I2C_ALGO_EM2800) {
> + return (I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL) &
> + ~I2C_FUNC_SMBUS_WRITE_BLOCK_DATA;
> + }
> +
> + return 0; /* BUG */
Please create a separate I2C register logic for bus B. It was a mistake
to reuse the existing I2C bus for logic for both buses (ok, actually,
no device currently uses 2 buses, as they simply don't read eeproms on
2 bus devices).
Btw, cx231xx has a similar issue: it has 3 buses. See how it was solved there:
drivers/media/usb/cx231xx/cx231xx-core.c: cx231xx_i2c_register(&dev->i2c_bus[0]);
drivers/media/usb/cx231xx/cx231xx-core.c: cx231xx_i2c_register(&dev->i2c_bus[1]);
drivers/media/usb/cx231xx/cx231xx-core.c: cx231xx_i2c_register(&dev->i2c_bus[2]);
Of course, the em28xx-cards will need to tell on what bus the tuner and
demods are. The em28xx I2C logic will also need to write to EM28XX_R06_I2C_CLK
if the bus is different - the windows driver is just stupid: it just precedes all
I2C writes by a write at reg 0x06 - we can certainly do better than that ;).
If you're in doubt on how to do it, I can seek for some time to address it
properly.
> }
>
> static struct i2c_algorithm em28xx_algo = {
> diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
> index 2d6d31a..b7c8134 100644
> --- a/drivers/media/usb/em28xx/em28xx.h
> +++ b/drivers/media/usb/em28xx/em28xx.h
> @@ -175,6 +175,12 @@
> /* time in msecs to wait for i2c writes to finish */
> #define EM2800_I2C_XFER_TIMEOUT 20
>
> +enum em28xx_i2c_algo_type {
> + EM28XX_I2C_ALGO_EM28XX,
> + EM28XX_I2C_ALGO_EM2800,
> + EM28XX_I2C_ALGO_EM25XX_BUS_B,
> +};
> +
> enum em28xx_mode {
> EM28XX_SUSPEND,
> EM28XX_ANALOG_MODE,
> @@ -510,6 +516,7 @@ struct em28xx {
> /* i2c i/o */
> struct i2c_adapter i2c_adap;
> struct i2c_client i2c_client;
> + enum em28xx_i2c_algo_type i2c_algo_type;
> unsigned char eeprom_addrwidth_16bit:1;
> /* video for linux */
> int users; /* user count for exclusive use */
--
Cheers,
Mauro
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